Catheter with distal interventional element

ABSTRACT

Systems and methods for removal of clot material from vessel lumens are disclosed. A medical device assembly can include a catheter having a lumen and a distal portion configured to be positioned at or adjacent a treatment site within a vessel. An expandable member has a first portion coupled to the distal portion of the catheter, and a second portion extending away from the catheter distal portion. An elongate shaft extends through the lumen of the catheter, and the second portion of the expandable member is releasably coupled to the shaft. When the shaft is slidably moved relative to the surrounding catheter, the second portion of the expandable member can be released from the shaft, and the shaft can be withdrawn or removed.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation of U.S. patent application Ser. No. 17/249,248, filed Feb. 24, 2021, which claims the benefit of priority to U.S. Provisional Patent Application No. 62/994,452, filed Mar. 25, 2020, each of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present technology relates generally to devices and methods for removing obstructions from body lumens. Some embodiments of the present technology relate to aspiration catheters having distally positioned interventional elements.

BACKGROUND

Many medical procedures use medical device(s) to remove an obstruction (such as clot material) from a body lumen, vessel, or other organ. An inherent risk in such procedures is that mobilizing or otherwise disturbing the obstruction can potentially create further harm if the obstruction or a fragment thereof dislodges from the retrieval device. If all or a portion of the obstruction breaks free from the device and flows downstream, it is highly likely that the free material will become trapped in smaller and more tortuous anatomy. In many cases, the physician will no longer be able to use the same retrieval device to again remove the obstruction because the device may be too large and/or immobile to move the device to the site of the new obstruction.

Procedures for treating ischemic stroke by restoring flow within the cerebral vasculature are subject to the above concerns. The brain relies on its arteries and veins to supply oxygenated blood from the heart and lungs and to remove carbon dioxide and cellular waste from brain tissue. Blockages that interfere with this blood supply eventually cause the brain tissue to stop functioning. If the disruption in blood occurs for a sufficient amount of time, the continued lack of nutrients and oxygen causes irreversible cell death. Accordingly, it is desirable to provide immediate medical treatment of an ischemic stroke.

To access the cerebral vasculature, a physician typically advances a catheter from a remote part of the body (typically a leg) through the abdominal vasculature and into the cerebral region of the vasculature. Once within the cerebral vasculature, the physician deploys a device for retrieval of the obstruction causing the blockage, for example an aspiration catheter. Concerns about dislodged obstructions or the migration of dislodged fragments increases the duration of the procedure at a time when restoration of blood flow is paramount. Furthermore, a physician might be unaware of one or more fragments that dislodge from the initial obstruction and cause blockage of smaller more distal vessels. Accordingly, there remains a need for improved devices and methods that can remove occlusions from body lumens and/or vessels.

SUMMARY

Many of the treatment systems of the present technology include an aspiration catheter for applying negative pressure at the treatment site to draw clot material into the lumen of the aspiration catheter and/or to secure clot material against a distal portion of the aspiration catheter (and/or other component of the treatment system). In some embodiments, an interventional element (e.g., an expandable member, a mesh, a braid, etc.) can be coupled to a distal end portion of the aspiration catheter and extend distally therefrom. While such a distally extending interventional element can be useful to reduce the risk of embolization and to facilitate flow arrest at the treatment site, the interventional element can make advancement of the aspiration catheter to the treatment site more difficult. In many cases, there may be an increased risk of damage to vessel walls when slidably advancing an aspiration catheter having a distally positioned interventional element through a patient's vasculature.

Accordingly, in some embodiments of the present technology, such a distally positioned interventional element can have a first end portion that is coupled to the aspiration catheter (e.g., coupled to a distal end portion of the aspiration catheter) and a second end portion that is coupled to a shaft (e.g., a microcatheter, core member, guide wire, etc.) that extends through a lumen of the aspiration catheter. By securing the second end portion of the interventional element to the shaft, the interventional element can be maintained in a low-profile configuration for advancement through the patient's vasculature. Once positioned at the treatment site, the shaft can be advanced relative to the aspiration catheter until the second end portion of the interventional element is released. For example, the interventional element can be coupled to the shaft using a rupturable connection (e.g., a low-density polyethylene tubing or other suitable connection member). As the shaft is advanced and pressure is exerted on the connection, the connection may rupture, tear, or otherwise release the second portion of the interventional element. Once released, the interventional element can assume its expanded form, for example expanding radially outwardly into apposition with the vessel wall. After this release, suction can be applied to aspirate clot material at the treatment site. The presence of the interventional element can function as a funnel-like element to help guide clot material into the aspiration catheter, and can also protect against embolization of any material that breaks away from the clot, for example by at least partially arresting blood flow at the treatment site.

The present technology is illustrated, for example, according to various aspects described below. Various examples of aspects of the present technology are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the present technology. It is noted that any of the dependent clauses may be combined in any combination, and placed into a respective independent clause. The other clauses can be presented in a similar manner.

Clause 1. A medical device assembly, comprising:

-   -   a catheter having a lumen and a distal portion configured to be         positioned at or adjacent a treatment site within a vessel;     -   an expandable member having a first portion coupled to the         distal portion of the catheter, the expandable member having a         second portion extending away from the catheter distal portion;         and     -   an elongate shaft extending through the lumen of the catheter,         the second portion of the expandable member being releasably         coupled to the shaft.

Clause 2. The assembly of any one of the Clauses herein, wherein the shaft is slidably moveable relative to the catheter between a first configuration and a second configuration, wherein in the first configuration, the first portion of the expandable member is positioned distal to the second portion of the expandable member such that the second portion is at least partially disposed within the catheter lumen, wherein in the second configuration, the first portion of the expandable member is positioned proximal to the second portion of the expandable member such that the second portion extends distally away from the catheter distal portion.

Clause 3. The assembly of any one of the Clauses herein, wherein the shaft is slidably moveable with respect to the catheter.

Clause 4. The assembly of any one of the Clauses herein, wherein the catheter comprises an aspiration catheter configured to be coupled at a proximal end portion to a suction source.

Clause 5. The assembly of any one of the Clauses herein, wherein slidable movement of the shaft causes slidable movement of the second portion of the expandable member relative to the first portion of the expandable member.

Clause 6. The assembly of any one of the Clauses herein, wherein the assembly is configured such that, upon distal advancement of the shaft relative to the catheter, the second portion of the expandable member is released from the shaft and allowed to self-expand.

Clause 7. The assembly of any one of the Clauses herein, wherein the expandable member comprises a braid or a mesh.

Clause 8. The assembly of any one of the Clauses herein, wherein the expandable member comprises a tubular element.

Clause 9. The assembly of any one of the Clauses herein, wherein the expandable member comprises a plurality of struts defining a plurality of cells, and wherein a proximal peak of at least one strut is coupled to the catheter.

Clause 10. The assembly of any one of the Clauses herein, wherein the expandable member is mechanically coupled to the catheter at a plurality of circumferential portions of the catheter.

Clause 11. The assembly of any one of the Clauses herein, wherein the expandable member is configured to engage a thrombus.

Clause 12. The assembly of any one of the Clauses herein, wherein the expandable member has a surface treatment along at least a portion of its surface to promote at least one of mechanical or chemical engagement between the expandable member and a clot.

Clause 13. The assembly of any one of the Clauses herein, wherein the surface treatment comprises at least one of surface etching or a polymer coating.

Clause 14. The assembly of any one of the Clauses herein, wherein the expandable member first portion is fixedly coupled to the catheter.

Clause 15. The assembly of any one of the Clauses herein, wherein a first coupling element extends over the first portion of the expandable member and secures the first portion of the expandable member to the distal portion of the catheter.

Clause 16. The assembly of any one of the Clauses herein, wherein the first coupling element comprises a tubular band.

Clause 17. The assembly of any one of the Clauses herein, wherein the first coupling element comprises a jacket.

Clause 18. The assembly of any one of the Clauses herein, wherein the catheter comprises an electrical conductor in electrical communication with the expandable member, the expandable member configured to receive an electrical signal via the electrical conductor that causes the expandable member to electrostatically engage a thrombus.

Clause 19. The assembly of any one of the Clauses herein, wherein the shaft comprises a microcatheter or guide wire.

Clause 20. The assembly of any one of the Clauses herein, wherein the expandable member is releasably coupled to the shaft via a second coupling element.

Clause 21. The assembly of any one of the Clauses herein, wherein the second coupling element comprises a rupturable fastener.

Clause 22. The assembly of any one of the Clauses herein, wherein the second coupling element comprises a band configured to circumferentially surround the second portion of the expandable member such that a proximal force applied to the expandable member can release the second portion of the expandable member from within the band.

Clause 23. The assembly of any one of the Clauses herein, wherein the second coupling element comprises a low-density polyethylene.

Clause 24. The assembly of any one of the Clauses herein, wherein the second coupling element circumferentially surrounds to the shaft.

Clause 25. The assembly of any one of the Clauses herein, further comprising a radiopaque marker disposed between the shaft and the second coupling element.

Clause 26. The assembly of any one of the Clauses herein, further comprising one or more radiopaque markers disposed on the catheter.

Clause 27. A medical device assembly, comprising:

-   -   an elongated tubular member having a lumen and a distal portion         configured to be positioned at or adjacent a treatment site         within a vessel;     -   an interventional element having a first portion coupled to the         distal portion of the catheter, the interventional element         having a second portion extending away from the tubular member;         and     -   an elongated shaft extending through the lumen of the tubular         member, the second portion of the interventional element being         releasably coupled to the shaft.

Clause 28. The assembly of any one of the Clauses herein, wherein the elongated tubular member comprises a catheter.

Clause 29. The assembly of any one of the Clauses herein, wherein the catheter comprises an aspiration catheter configured to be fluidically coupled to a suction source.

Clause 30. The assembly of any one of the Clauses herein, wherein the interventional element comprises an embolic filter.

Clause 31. The assembly of any one of the Clauses herein, wherein the interventional element comprises a braid or a mesh.

Clause 32. The assembly of any one of the Clauses herein, wherein the interventional element is self-expandable.

Clause 33. The assembly of any one of the Clauses herein, wherein the shaft comprises a microcatheter.

Clause 34. The assembly of any one of the Clauses herein, wherein the shaft comprises a core member or guide wire.

Clause 35. The assembly of any one of the Clauses herein, wherein the shaft is slidably moveable with respect to the tubular member.

Clause 36. The assembly of any one of the Clauses herein, wherein slidable movement of the shaft causes slidable movement of the second portion of the interventional element relative to the first portion of the interventional element.

Clause 37. The assembly of any one of the Clauses herein, wherein the assembly is configured such that, upon distal advancement of the shaft relative to the tubular member, the second portion of the interventional element is released from the shaft.

Clause 38. The assembly of any one of the Clauses herein, wherein the interventional element is mechanically coupled to the tubular member at a plurality of circumferential portions of the tubular member.

Clause 39. The assembly of any one of the Clauses herein, wherein the interventional element has a surface treatment along at least a portion of its surface to promote at least one of mechanical or chemical engagement between the interventional element and a thrombus.

Clause 40. The assembly of any one of the Clauses herein, wherein the surface treatment comprises at least one of surface etching or a polymer coating.

Clause 41. The assembly of any one of the Clauses herein, wherein the interventional element first portion is fixedly coupled to the tubular member.

Clause 42. The assembly of any one of the Clauses herein, wherein a first coupling element extends over the first portion of the interventional element and secures the first portion of the interventional element to the distal portion of the tubular member.

Clause 43. The assembly of any one of the Clauses herein, wherein the first coupling element comprises a tubular band.

Clause 44. The assembly of any one of the Clauses herein, wherein the first coupling element comprises a jacket.

Clause 45. The assembly of any one of the Clauses herein, wherein the tubular member comprises an electrical conductor in electrical communication with the interventional element, the interventional element configured to receive an electrical signal via the electrical conductor that causes the interventional element to electrostatically engage a thrombus.

Clause 46. The assembly of any one of the Clauses herein, wherein the interventional element is releasably coupled to the shaft via a second coupling element.

Clause 47. The assembly of any one of the Clauses herein, wherein the second coupling element comprises a rupturable fastener.

Clause 48. The assembly of any one of the Clauses herein, wherein the second coupling element comprises a band configured to circumferentially surround the second portion of the interventional element such that a proximal force applied to the interventional element can release the second portion of the interventional element from within the band.

Clause 49. The assembly of any one of the Clauses herein, wherein the second coupling element comprises a low-density polyethylene.

Clause 50. The assembly of any one of the Clauses herein, wherein the second coupling circumferentially surrounds to the shaft.

Clause 51. The assembly of any one of the Clauses herein, further comprising a radiopaque marker disposed between the shaft and the second coupling element.

Clause 52. The assembly of any one of the Clauses herein, further comprising one or more radiopaque markers disposed on the tubular member.

Clause 53. A medical device assembly, comprising:

-   -   a catheter having a lumen and a distal portion;     -   an elongate shaft slidably received within the catheter lumen;     -   an interventional element having a first portion coupled to the         catheter distal portion and a second portion coupled to the         elongate shaft, wherein relative movement of the elongate shaft         and the catheter causes at least one of the first portion or the         second portion to be released.

Clause 54. The assembly of any one of the Clauses herein, wherein the interventional element comprises a braid or mesh.

Clause 55. The assembly of any one of the Clauses herein, wherein the interventional element is self-expandable.

Clause 56. The assembly of any one of the Clauses herein, wherein the interventional element comprises a tubular member.

Clause 57. The assembly of any one of the Clauses herein, wherein the relative movement comprises longitudinal movement.

Clause 58. The assembly of any one of the Clauses herein, wherein the relative movement comprises rotational movement.

Clause 59. The assembly of any one of the Clauses herein, wherein the relative movement causes the first portion of the interventional element to be released from the catheter distal portion.

Clause 60. The assembly of any one of the Clauses herein, wherein the relative movement causes the second portion of the interventional element to be released from the catheter distal portion.

Clause 61. The assembly of any one of the Clauses herein, wherein the first portion of the interventional element is coupled to the catheter distal portion via a band.

Clause 62. The assembly of any one of the Clauses herein, wherein the second portion of the interventional element is coupled to the shaft via a band.

Clause 63. The assembly of any one of the Clauses herein, wherein the second portion of the interventional element is coupled to the shaft via a rupturable fastener.

Clause 64. The assembly of any one of the Clauses herein, wherein the shaft comprises a microcatheter.

Clause 65. The assembly of any one of the Clauses herein, wherein the shaft comprises a core member or guide wire.

Clause 66. A method comprising:

-   -   disposing a medical device assembly within a vessel at or         adjacent a treatment site, the assembly comprising a catheter         having a lumen and a distal end portion, an elongated shaft         slidably received within the catheter lumen, and an         interventional element having a first end portion coupled to the         distal end portion of the catheter and a second end portion         releasably coupled to the shaft; and     -   moving the shaft relative to the catheter, thereby releasing the         second end portion of the interventional element from the shaft.

Clause 67. The method of any one of the Clauses herein, further comprising applying suction to the catheter to aspirate the treatment site.

Clause 68. The method of any one of the Clauses herein, wherein aspirating the treatment site comprises drawing at least a portion of a thrombus into the catheter lumen.

Clause 69. The method of any one of the Clauses herein, further comprising at least partially arresting blood flow at the treatment site via the released interventional element.

Clause 70. The method of any one of the Clauses herein, wherein moving the shaft relative to the catheter comprises proximally retracting the shaft relative to the catheter.

Clause 71. The method of any one of the Clauses herein, wherein moving the shaft comprises distally advancing the shaft relative to the catheter.

Clause 72. The method of any one of the Clauses herein, wherein moving the shaft comprises rotating the shaft relative to the catheter.

Clause 73. The method of any one of the Clauses herein, further comprising removing the shaft from the catheter lumen following release of the interventional element.

Clause 74. The method of any one of the Clauses herein, wherein moving the shaft relative to the catheter comprises distally advancing the shaft from a first position to a second position, wherein in the first position the second end portion of the interventional element is disposed within the catheter lumen and proximal to the first end portion of the interventional element, and wherein in the second position the second end portion of the interventional element is disposed distal to the catheter distal end portion and distal to the first end portion of the interventional element.

Clause 75. The method of any one of the Clauses herein, wherein following release of the interventional element, the interventional element self-expands into apposition with a wall of the vessel.

Additional features and advantages of the present technology are described below, and in part will be apparent from the description, or may be learned by practice of the present technology. The advantages of the present technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present technology can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on illustrating clearly the principles of the present disclosure.

FIG. 1 shows a perspective view of a system for retrieving material from a body lumen, in accordance with one or more embodiments of the present technology.

FIG. 2 illustrates an enlarged detail view of a portion of the medical device assembly shown in FIG. 1 .

FIGS. 3A-3C illustrate a method of deploying the interventional element of the medical device assembly shown in FIG. 2 .

FIG. 4 illustrates the medical device assembly following removal of the microcatheter and core member.

FIG. 5 illustrates the medical device assembly following deployment of a second interventional element at the treatment site.

DETAILED DESCRIPTION I. Overview of Example Treatment Systems

The present technology provides devices, systems, and methods for removing clot material from a blood vessel lumen. Although many of the embodiments are described below with respect to devices, systems, and methods for treating a cerebral or intracranial embolism, other applications and other embodiments in addition to those described herein are within the scope of the technology. For example, the treatment systems and methods of the present technology may be used to remove emboli from body lumens other than blood vessels (e.g., the digestive tract, etc.) and/or may be used to remove emboli from blood vessels outside of the brain (e.g., pulmonary, abdominal, cervical, or thoracic blood vessels, or peripheral blood vessels including those within the legs or arms, etc.). In addition, the treatment systems and methods of the present technology may be used to remove luminal obstructions other than clot material (e.g., plaque, resected tissue, foreign material, etc.).

FIG. 1 illustrates a view of a treatment system 100 according to one or more embodiments of the present technology. As shown in FIG. 1 , the treatment system 100 can include a medical device assembly 101 and a suction source 103. The assembly 101 includes a proximal portion 101 a configured to be coupled to the suction source 103 and a distal portion 101 b configured to be intravascularly positioned within a blood vessel (such as an intracranial blood vessel) at a treatment site at or proximate a thrombus. The medical device assembly 101 includes a handle 102 at the proximal portion 100 a, a distal portion 100 b opposite the proximal portion 100 a, and a plurality of elongated shafts or tubular members extending therebetween. For example, in some embodiments, such as that shown in FIG. 1 , the medical device assembly 101 includes a first or guide catheter 105 (e.g., a balloon-guide catheter), a second or distal access catheter 107 (e.g., an aspiration catheter) configured to be slidably disposed within a lumen of the guide catheter 105, a microcatheter configured to be slidably disposed within a lumen of the distal access catheter 107, and a guidewire or core member 111 configured to be slidably disposed within a lumen of the microcatheter 109. In some embodiments, the medical device assembly 101 does not include one or more of the catheters 105, 107, 109, or the core member 111.

In operation, one or more of the catheters 105, 107, 109 can be used as an aspiration catheter to remove a clot or other material such as plaques or foreign bodies from vasculature of a patient. In such examples, a vacuum may be applied to proximal end of the distal access catheter 107 (e.g., via suction source 103) to draw a clot or other blockage into an inner lumen of the distal access catheter 107. Such aspiration may be used in various medical procedures, such as a medical procedure to treat an ischemic insult, which may occur due to occlusion of a blood vessel (arterial or venous) that deprives brain tissue, heart tissue or other tissues of oxygen-carrying blood.

An interventional element (not shown in FIG. 1 ) can be coupled to a distal end portion of the distal access catheter 107 to improve aspiration. The interventional element can take the form an expandable member such as a braid or a mesh that is configured to arrest blood flow, engage a thrombus, and/or to serve as an embolic filter. During aspiration, the interventional element can have a first end fixedly secured to the distal access catheter 107 and a second, free end that is allowed to expand, e.g., into apposition with the vessel wall. In this state, the interventional element can operate as a funnel to facilitate aspiration, may engage clot material during or after aspiration, and/or may at least partially arrest blood flow at the treatment site. As described in more detail below with respect to FIGS. 2-5 , to avoid damage to the vessel wall while distally advancing the distal access catheter 107 to the treatment site, the interventional element can initially be releasably coupled at one end to the microcatheter 109 for delivery. Once the distal access catheter 107 is positioned at or near the treatment site, the interventional element can be released from the microcatheter 109 (e.g., by relative movement of the microcatheter 109 with respect to the distal access catheter 107), thereby allowing the interventional element to radially expand while remaining coupled at one end to the distal end of the distal access catheter 107. The structure and operation of the interventional element is described in more detail below with respect to FIGS. 2-5 .

With continued reference to FIG. 1 , in some examples, one or more of the catheters (e.g., the distal access catheter 107 and/or microcatheter 109) can be configured to access relatively distal locations in a patient including, for example, the middle cerebral artery (MCA), internal carotid artery (ICA), the Circle of Willis, and tissue sites more distal than the MCA, ICA, and the Circle of Willis. The MCA, as well as other vasculature in the brain or other relatively distal tissue sites (e.g., relative to the vascular access point), may be relatively difficult to reach with a catheter, due at least in part to the tortuous pathway (e.g., comprising relatively sharp twists or turns) through the vasculature to reach these tissue sites. As such, the catheter may be structurally configured to be relatively flexible, pushable, and relatively kink- and buckle-resistant, so that it may resist buckling when a pushing force is applied to a relatively proximal section of the catheter to advance the catheter distally through vasculature, and so that it may resist kinking when traversing around a tight turn in the vasculature. In some examples, the catheter is configured to substantially conform to the curvature of the vasculature. In addition, in some examples, the catheter has a column strength and flexibility that allow at least distal portion of the catheter to be navigated from a femoral artery, through the aorta of the patient, and into the intracranial vascular system of the patient, e.g., to reach a relatively distal treatment site.

Although primarily described as being used to reach relatively distal vasculature sites, the distal access catheter 107 may also be configured to be used with other target tissue sites. For example, distal access catheter 107 may be used to access tissue sites throughout the coronary and peripheral vasculature, the gastrointestinal tract, the urethra, ureters, fallopian tubes, veins and other body lumens.

According to some embodiments, the catheters 105, 107, and 109 can each be formed as a generally tubular member extending along and about a central axis and terminating in respective distal ends. According to some embodiments, the microcatheter 109 is generally constructed to track over a conventional guidewire in the cervical anatomy and into the cerebral vessels associated with the brain and may also be chosen according to several standard designs that are generally available. Accordingly, the microcatheter 109 can have a length that is at least 125 cm long, and more particularly may be between about 125 cm and about 175 cm long. In some embodiments, the microcatheter can have a lumen diameter of less than about 0.03″, such as about 0.017″, 0.021″, or 0.027″ lumen diameter. Other designs and dimensions are contemplated.

The distal access catheter 107 can be sized and configured to be slidably receive the microcatheter 109 therethrough. As noted above, the distal access catheter 107 can be coupled at a proximal portion to a suction source 103 such as a pump or syringe in order to supply negative pressure to a treatment site. In various embodiments, the distal access catheter 107 can have a length that is at least 125 cm long, and more particularly may be between about 125 cm and about 175 cm long. In some embodiments, the microcatheter 109 can be an aspiration catheter. The distal access catheter can have a lumen diameter of a between about 0.05″ and about 0.09″, for example about 0.061″, about 0.068″, or about 0.071″ lumen diameter. The distal access catheter 107 can have a maximum outer diameter of between about 0.06″ to about 0.1″, for example about 0.083″, or about 0.0855″. Other designs and dimensions are contemplated.

The guide catheter 105 can be sized and configured to slidably receive both the distal access catheter 107 and the microcatheter 109 therethrough. In some embodiments, the guide catheter 105 is a balloon-guide catheter having an inflatable balloon or other expandable member that can be used to anchor the guide catheter 105 with respect to a surrounding vessel. In operation the guide catheter 105 can first be advanced through a vessel and then a balloon can be expanded to anchor the guide catheter 105 in place and/or arrest blood flow from areas proximal of the balloon. Next, the distal access catheter 107 and the microcatheter 109 can be advanced together through the guide catheter 105 until they each extend distally beyond the distal end of the guide catheter 105. As described in more detail below, an interventional element (e.g., a radially expandable member, braid, mesh, etc.) can be coupled at a first end to a distal end portion of the distal access catheter 107. The interventional element can facilitate engagement with the clot, improve aspiration, and reduce the risk of embolism at the treatment site. During advancement, the interventional element can be removably coupled at its second end portion to the microcatheter. Once the distal access catheter 107 is in positioned such that its distal end is adjacent a treatment site (e.g., a site of a blood clot within the vessel), the interventional element can be released from the microcatheter 109 (e.g., via distal advancement of the microcatheter), and the interventional element may expand into apposition with the vessel wall. Suction can then be applied to aspirate the treatment site.

According to some embodiments, the bodies of the catheters 105, 107, 109 can be made from various thermoplastics, e.g., polytetrafluoroethylene (PTFE or TEFLON®), fluorinated ethylene propylene (FEP), high-density polyethylene (HDPE), polyether ether ketone (PEEK), etc., which can optionally be lined on the inner surface of the catheters or an adjacent surface with a hydrophilic material such as polyvinylpyrrolidone (PVP) or some other plastic coating. Additionally, either surface can be coated with various combinations of different materials, depending upon the desired results.

In various embodiments, the core member 111 can be a solid pushwire or guidewire. Additionally or alternatively, the core member 111 can include a hollow wire, hypotube, braid, coil, or other suitable member(s), or a combination of wire(s), tube(s), braid(s), coil(s), etc. The core member 111 can include a laser-cut hypotube having a spiral cut pattern (or other pattern of cut voids) formed in its sidewall along at least a portion of its length. In some embodiments, the core member 111 can be made of stainless steel (e.g., 304 SS), Nitinol, and/or other alloy. In at least some embodiments, the core member can have a laser cut pattern to achieve the desired mechanical characteristics (e.g., column strength, flexibility, kink-resistance, etc.).

II. Select Examples of Catheters Having Distal Interventional Elements

FIG. 2 illustrates an enlarged detail view of the distal portion 101 b of the medical device assembly 100 shown in FIG. 1 . As noted previously, a core member 111 slidably extends through a lumen of the microcatheter 109, which in turn slidably extends through a lumen of the distal access catheter 107. An interventional element 201 extends between a first coupling region 203 disposed at a distal end portion 107 b of the distal access catheter 107 and a second coupling region 205 disposed on the microcatheter 109. In particular, the interventional element 201 can include a first portion 201 a (e.g., a first end portion or a proximal end portion in the illustrated configuration) coupled to the distal access catheter 107 via a first coupling element 207 at the first coupling region 203. The interventional element can further include a second portion 201 b (e.g., a second end portion or a distal end portion in the illustrated configuration) that is coupled to the microcatheter 109 via a second coupling element 209 disposed at the second coupling region 205.

The interventional element 201 can be configured to be releasably coupled to the microcatheter 109 to maintain the interventional element 201 in a low-profile state for delivery to the treatment site. As described in more detail below with respect to FIGS. 3A-3C, once the second portion 201 b of the interventional element 201 is released from the second coupling element 209, at least a portion of the interventional element 201 can expand radially outwardly, for example into apposition with the vessel wall. This may enable, for example, the interventional element 201 to engage with a clot (e.g., thrombus or embolism) during an aspiration procedure, such as, but not limited to, a medical procedure using aspiration for acute stroke thrombectomy. The interventional element 201 may help improve aspiration of the clot into the catheter by providing a relatively large diameter and interior space for the clot to engage with the distal access catheter 107 compared to examples in which an otherwise similar catheter does not include an interventional element 201. For example, such a catheter that does not include an interventional element 201 may have limited radial expansion due to a structural support member that extends to the distal end of the catheter, and may thus make it harder to aspirate a clot (e.g., due to a smaller cross-sectional dimension of the distal end of the catheter). The interventional element 201 may overcome such radial expansion limitations, including by increasing clot engagement, reducing the amount of time required for revascularization, and increasing revascularization success rates for various procedures, as compared to similar procedures used with catheters that do not include an interventional element 201 to engage a clot.

In some examples, an inner surface of the interventional element 201 may comprise a surface treatment configured to promote at least one of mechanical or chemical engagement between the inner surface and the clot. In some examples, a coating may be applied to portions of the inner surface of the interventional element 201 (e.g., the inner surface of the struts), or the surfaces may be textured via etching or otherwise roughened (or rougher) in comparison to the outer surface of the interventional element 201 to better mechanically engage the clot.

In some examples, clot engagement with the interventional element 201 may be enhanced by delivering electrical energy to the interventional element 201. For example, a source of electrical energy (e.g., an electrical signal generator) may deliver an electrical signal to the interventional element 201 via one or more electrical conductors (not shown) electrically coupled to the interventional element 201. The electrical energy may be positively charged to electrostatically engage a clot. Characteristics of the electrical energy may be adjusted to better engage the clot, such as polarity, or an amount or type of current delivered. For example, pulsed direct current may be employed, optionally with a non-square and/or non-negative waveform. The electrical conductors can extend through inner lumen of the distal access catheter 107, can extend along an outer surface of distal access catheter 107, can be embedded in a wall of the distal access catheter 107, or have any other suitable configuration.

According to some embodiments, the interventional element 201 may include a mesh formed of a plurality of braided filaments that have been heat-set to assume a predetermined shape when the mesh is in an expanded, unconstrained state. Example shapes include a tubular shape, a cylindrical shape, a conical shape, a globular shape, an oblate spheroid shape, etc. The mesh may be formed of metal wires, polymer wires, or both, and the wires may have shape memory and/or superelastic properties. The mesh may be formed of 12, 16, 18, 24, 32, 36, 48, 64, 72, 96, 128, or 144 filaments. The mesh may be formed of a range of filament or wire sizes, such as wires having a diameter of from about 0.0004 inches to about 0.0050 inches, or of from about 0.0009 inches to about 0.0012 inches. In some embodiments, all of the filaments of the braided mesh may have the same diameter. For example, in some embodiments, all of the filaments have a diameter of about 0.001 inches. In some embodiments, some of the filaments may have different cross-sectional diameters. For example, some of the filaments may have a slightly thicker diameter to impart additional strength to the braided layers. In some embodiments, some of the filaments can have a diameter of about 0.001 inches, and some of the filaments can have a diameter of greater than 0.001 inches. The thicker filaments may impart greater strength to the braid without significantly increasing the device delivery profile, with the thinner wires offering some strength while filling-out the braid matrix density.

With continued reference to FIG. 2 , the first coupling element 207 secures the first portion 201 a of the interventional element 201 to the distal end portion 107 b of the distal access catheter 107. The first coupling element 207 can include, for example, a fastener extending over the first portion 201 a of the interventional element 201 and over the distal end portion 107 b, for example at least partially circumferentially surrounding the interventional element 201 such that the interventional element is disposed radially between the first coupling element 207 and the outer surface of the distal access catheter 107. The first coupling element 207 can be configured to fixedly, non-releasably, or substantially permanently secure the first portion 201 a of the interventional element 201 to the distal access catheter 107. In other embodiments, the first coupling element 207 can be configured to releasably secure the interventional element 201 to the distal access catheter 107.

In various embodiments, the first coupling element 207 can include a tube, band, jacket, sheath, adhesive, weld, or any other suitable element configured to secure, fasten, or restrain the first portion 201 a of the interventional element 201 with respect to the distal end portion 107 b of the distal access catheter 107. The first coupling element 207 can be made of a polymer (e.g., polyether block amide or other suitable thermoplastic polymer), metal, or any other suitable material. Although the first coupling element 207 is illustrated as being disposed adjacent a distal terminus of the distal access catheter 107, in other embodiments the first coupling element 207 can be at least partially spaced proximally away from a distal terminus of the distal access catheter 107.

The microcatheter 109 slidably extends through the lumen 211 of the distal access catheter 107. In the illustrated embodiment, the microcatheter 109 has a lumen through which the core member 111 slidably extends. However, in other embodiments the microcatheter 109 can be replaced with any suitable shaft or member, for example a core member, a guide wire, an elongate shaft or member, etc. In such embodiments, the second coupling element 209 can be carried by or otherwise coupled to such a core member, guide wire, shaft, etc.

As shown in FIG. 2 , the interventional element 201 tapers radially inwardly from the first portion 201 a to the second portion 201 b, with the second portion 201 b being coupled to the microcatheter 109 via the second coupling element 209. The second coupling element 209 can include, for example, a fastener extending over the second portion 201 b of the interventional element 201 and over the microcatheter 109 within the second coupling region 205. For example, the second coupling element 209 can at least partially circumferentially surround the interventional element 201 such that the second portion 201 b of the interventional element 201 is disposed radially between the second coupling element 209 and the outer surface of the microcatheter 109.

The second coupling element 209 can be configured to releasably, non-permanently secure the second portion 201 b of the interventional element 201 to the microcatheter 109. For example, the second coupling element 209 can be configured to break, tear, split, or rupture, thereby releasing the second portion 201 b of the interventional element 201. In some embodiments, the second coupling element 209 can be configured such that, upon distal advancement of the microcatheter 109 relative to the distal access catheter 107, the second portion 201 b of the interventional element 201 may be slidably released from the second coupling element 209, for example slipping out from underneath the second coupling element 209. In other embodiments, the first coupling element 207 can be configured to fixedly, permanently, or non-releasably secure the interventional element 201 to the microcatheter 109.

In various embodiments, the second coupling element 209 can include a tube, band, jacket, sheath, adhesive, weld, or any other suitable element configured to secure, fasten, or restrain the second portion 201 b of the interventional element 201 with respect to the microcatheter 109. The second coupling element 207 can be made of a polymer (e.g., low-density polyethylene or other suitable polymer), metal, or any other suitable material.

In the embodiment illustrated in FIG. 2 , the second coupling element 209 is disposed over a mounting element 213. In some embodiments, the mounting element 213 can be a radiopaque marker, for example a radiopaque band, tube, strip, or other element coupled to the microcatheter 109. For example, the mounting element 213 can include platinum or other radiopaque material, thereby enabling visualization under fluoroscopy. The second portion 201 b of the interventional element 201 and the second coupling element 209 can both extend at least partially circumferentially around the mounting element 213 such that at least a portion of the second portion 201 b of the interventional element 201 is disposed radially between the mounting element 213 and the second coupling element 209. In some embodiments, the mounting element 213 can be rotatably mounted to the microcatheter 109, while being longitudinally constrained to preclude longitudinal sliding of the mounting element 213 with respect to the microcatheter 109. In this configuration, the microcatheter 109 may rotate with respect to the distal access catheter 107 without applying undue torque to the interventional element 201, since the mounting element 213 onto which the second portion 201 b is secured is free to rotate with respect to the microcatheter 109. In other embodiments, the mounting element 213 can be omitted and/or may be non-rotatably coupled to the microcatheter 109.

Additionally, in some embodiments one or more radiopaque markers can be disposed at various locations along the microcatheter 109 to facilitate visualization of the relative movement of the microcatheter 109 with respect to the distal access catheter 107. For example, a proximal marker 215 can be coupled to the microcatheter 109 at a position proximal to the second coupling region 205, and a distal marker 217 can be coupled to the microcatheter 109 at a position distal to the second coupling region 205. Such markers can take the form of bands, tubes, strips, beads, or other elements coupled to the microcatheter 109, and can include platinum or other radiopaque material, thereby enabling visualization of the markers under fluoroscopy. As discussed in more detail below with respect to FIGS. 3A-3C, in some embodiments the proximal and distal markers 215, 217 can be used to guide a clinician in positioning the microcatheter 109 with respect to the distal access catheter 107 for delivery and deployment of the interventional element 201.

FIGS. 3A-3C illustrate a method of deploying the interventional element of the medical device assembly shown in FIG. 2 . FIG. 3A illustrates the assembly 101 in a delivery configuration. As noted previously, while distally advancing the distal access catheter 107 through a patient's vasculature, any radially protruding features risk inflicting damage on the surrounding vessel walls. As such, while a radially protruding interventional element 201 can be clinically beneficial during aspiration, it may be desirable to position the interventional element 201 in a delivery configuration such that contact with the vessel wall is reduced or eliminated.

As shown in FIG. 3A, the microcatheter 109 can be positioned relative to the distal access catheter 107 such that the second coupling element 209 (which secures the second portion 201 b of the interventional element 201 to the microcatheter 109) is disposed proximal to the first coupling element 207 (which secures the first portion 201 a of the interventional element 201 to the distal access catheter 107). As such, in this state, the interventional element 201 can be at least partially everted or inverted, with the second portion 201 b extending proximally away from the first portion 201 a. Additionally, some or all of the interventional element 201 can be disposed within the lumen 211 of the distal access catheter 107. In this position, the interventional element 201 is both radially constrained and separated from the surrounding wall of the vessel V via the distal access catheter 107.

In some embodiments, the distal marker 217 can aid a clinician in achieving this relative positioning of the distal access catheter 107 and the microcatheter 109. For example, when the distal marker 217 is positioned at or near a distal terminus of the distal access catheter 107, the second coupling element 209 can be positioned within the lumen 211 of the distal access catheter 107. This visibility can aid a clinician in avoiding over-retracting the microcatheter 109 with respect to the distal access catheter 107, as proximally withdrawing the microcatheter 109 too far would risk prematurely releasing the second portion 201 b of the interventional element 201 from the second coupling element 209 while the second portion 201 b of the interventional element 201 is disposed at least partially within the lumen 211 of the distal access catheter 107. In some embodiments, at least a portion of the distal access catheter 107 can be visible under fluoroscopy, for example including a radiopaque band or element disposed at or near its distal end.

Once in position at or near the treatment site, the microcatheter 109 can be distally advanced relative to the distal access catheter 107 (or, equivalently, the distal access catheter 107 can be proximally retracted relative to the microcatheter 109), such that the interventional element 201 moves from within the lumen of the distal access catheter 107 to being at least partially outside the lumen of the distal access catheter 107. As shown in FIG. 3B, the second coupling element 209 of the microcatheter 109 can be positioned distal to the first coupling element 207 of the distal access catheter 107, such that the second portion 201 b of the interventional element is disposed distal to the first portion 201 a of the interventional element. As such, in this configuration, the first portion 201 a of the interventional element 201 is positioned proximal to the second portion 201 b of the interventional element 201 such that the second portion 201 b extends distally away from the distal end of the distal access catheter 107. In the pre-deployment stage of FIG. 3B, the second portion 201 b of the interventional element 201 can remain secured to the microcatheter 109 via the second coupling element 209, such that the interventional element 201 retains a low-profile, radially constrained configuration. In some embodiments, the assembly can be advanced through the patient's vasculature while in this configuration.

FIG. 3C illustrates the assembly 101 following deployment of the interventional element 201 at or near the treatment site. To deploy the interventional element 201, the microcatheter 109 can be distally advanced relative to the distal access catheter 107 (or the distal access catheter 107 can be proximally retracted relative to the microcatheter 109), thereby causing the second portion 201 b of the interventional element to be released from the second coupling element 209. For example, the second coupling element 209 can rupture, tear, or break to release the second portion 201 b of the interventional element 201. Once released, the interventional element 201 can assume an expanded configuration, for example self-expanding into apposition with walls of the vessel V. As illustrated, the first portion 201 a of the interventional element 201 can remain fixedly secured to the distal access catheter 107 via the first coupling element 207.

In the expanded state, the interventional element 201 can facilitate retrieval of clot material from the treatment site. For example, the interventional element 201 can function as a funnel-like element to help guide clot material into the aspiration catheter, and can also protect against embolization of any material that breaks away from the clot. In some embodiments, the interventional element 201 can be configured to at least partially arrest blood flow at the treatment site, thereby reducing the risk of distal embolization. For example, the interventional element 201 can have a sufficiently low porosity and/or other characteristics that impede blood flow therethrough. As such, when deployed as in FIG. 3C, blood flow can be at least partially arrested. Such flow arrest can improve the efficacy of aspiration at the treatment site, as well as reducing the risk of embolization due to distally flowing blood carrying clot material downstream within the vessel V.

In some embodiments, aspiration can be initiated while the microcatheter 109 remains in position at or near the treatment site. In certain cases, the microcatheter 109 can be removed following deployment of the interventional element 201. For example, as shown in FIG. 4 , with the microcatheter 109 and the core member 111 removed, the distal access catheter 107 can aspirate the treatment site (e.g., via suction applied via a suction source coupled to a proximal portion of the distal access catheter 107), thereby drawing clot material, plaque, or other material into the lumen of the distal access catheter 107. In various embodiments, the treatment site can be aspirated continuously before, during, or after deployment of the interventional element 201 as well as before, during, or after retraction of the microcatheter 109 through the distal access catheter 107.

In some embodiments, the distal access catheter 107 can be used in conjunction with a second interventional element configured to be deployed distal to the first interventional element 201. For example, as shown in FIG. 5 , a second interventional element 501 can be coupled to a distal end of the core member 111 and deployed at or adjacent the treatment site. The second interventional element 501 can be delivered through the microcatheter 109 in a constrained, low-profile configuration and transitioned into the expanded configuration at the treatment site. In some embodiments, the second interventional element 501 can be configured to engage clot material, for example being deployed while positioned radially adjacent a thrombus or at least partially distal to a thrombus.

In some embodiments the second interventional element 501 can be a thrombectomy device. The second interventional element 501 can have a low-profile, constrained or compressed configuration (not shown) for intravascular delivery to the treatment site within the microcatheter 109, and an expanded configuration for securing and/or engaging clot material and/or for restoring blood flow at the treatment site. In some embodiments, the second interventional element 501 is a mesh structure (e.g., a braid, a stent, etc.) formed of a superelastic material (e.g., Nitinol) or other resilient or self-expanding material configured to self-expand when released from the microcatheter 109. In some embodiments, the body of the second interventional element 501 can be generally tubular (e.g., cylindrical), and a proximal portion of the second interventional element 501 can taper proximally to a junction with the core member 111.

In various embodiments, the second interventional element 501 can take any number of forms, for example a removal device, a thrombectomy device, or other suitable medical device. For example, in some embodiments the second interventional element 501 may be a stent and/or stent retriever, such as Medtronic's Solitaire™ Revascularization Device, Stryker Neurovascular's Trevo® ProVue™ Stentriever, or other suitable devices. In some embodiments, the second interventional element 501 may be a coiled wire, a weave, and/or a braid formed of a plurality of braided filaments. Examples of suitable second interventional elements 501 include any of those disclosed in U.S. Pat. No. 7,300,458, filed Nov. 5, 2007, U.S. Pat. No. 8,940,003, filed Nov. 22, 2010, U.S. Pat. No. 9,039,749, filed Oct. 1, 2010, and U.S. Pat. No. 8,066,757, filed Dec. 28, 2010, each of which is incorporated by reference herein in its entirety.

III. Conclusion

This disclosure is not intended to be exhaustive or to limit the present technology to the precise forms disclosed herein. Although specific embodiments are disclosed herein for illustrative purposes, various equivalent modifications are possible without deviating from the present technology, as those of ordinary skill in the relevant art will recognize. In some cases, well-known structures and functions have not been shown and/or described in detail to avoid unnecessarily obscuring the description of the embodiments of the present technology. Although steps of methods may be presented herein in a particular order, in alternative embodiments the steps may have another suitable order. Similarly, certain aspects of the present technology disclosed in the context of particular embodiments can be combined or eliminated in other embodiments. Furthermore, while advantages associated with certain embodiments may have been disclosed in the context of those embodiments, other embodiments can also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages or other advantages disclosed herein to fall within the scope of the present technology. Accordingly, this disclosure and associated technology can encompass other embodiments not expressly shown and/or described herein.

Throughout this disclosure, the singular terms “a,” “an,” and “the” include plural referents unless the context clearly indicates otherwise. Similarly, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in reference to a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of the items in the list. Additionally, the terms “comprising” and the like are used throughout this disclosure to mean including at least the recited feature(s) such that any greater number of the same feature(s) and/or one or more additional types of features are not precluded. Directional terms, such as “upper,” “lower,” “front,” “back,” “vertical,” and “horizontal,” may be used herein to express and clarify the relationship between various elements. It should be understood that such terms do not denote absolute orientation. Reference herein to “one embodiment,” “an embodiment,” or similar formulations means that a particular feature, structure, operation, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present technology. Thus, the appearances of such phrases or formulations herein are not necessarily all referring to the same embodiment. Furthermore, various particular features, structures, operations, or characteristics may be combined in any suitable manner in one or more embodiments. 

1. (canceled)
 2. A method comprising: disposing a medical device assembly within a vessel at or adjacent a treatment site, the medical device assembly comprising: a catheter having a lumen and a distal end portion, an elongate shaft slidably received within the lumen of the catheter, and an interventional element having a first end portion coupled to the distal end portion of the catheter and a second end portion releasably coupled to the elongate shaft; and advancing the elongate shaft distally relative to the catheter to release the second end portion of the interventional element from the elongate shaft and cause the second end portion to assume an expanded configuration in which the second end portion defines a distal perimeter having a greater diameter than the first end portion of the interventional element.
 3. The method of claim 2, further comprising applying suction to the catheter to aspirate the treatment site.
 4. The method of claim 2, wherein aspirating the treatment site comprises drawing at least a portion of a thrombus into the lumen of the catheter.
 5. The method of claim 2, further comprising at least partially arresting blood flow at the treatment site via the interventional element.
 6. The method of claim 2, wherein advancing the elongate shaft distally relative to the catheter comprises distally advancing the elongate shaft from a first position to a second position, wherein in the first position, the second end portion of the interventional element is at least partially disposed within the lumen of the catheter and proximal to the first end portion of the interventional element, and wherein in the second position, the second end portion of the interventional element is disposed distal to the distal end portion of the catheter and distal to the first end portion of the interventional element.
 7. The method of claim 2, wherein following release of the interventional element, the interventional element self-expands into apposition with a wall of the vessel.
 8. The method of claim 2, wherein the interventional element comprises a mesh.
 9. The method of claim 2, wherein the intervention element comprises an embolic filter.
 10. The method of claim 2, wherein the second end portion is releasably coupled to the elongate shaft by a coupling element, and wherein the second end portion is released from the elongate shaft by breaking the coupling element.
 11. The method of claim 2, wherein the second end portion is releasably coupled to the elongate shaft by a coupling element, and wherein the second end portion is released from the elongate shaft by causing the second end portion to slide out from the coupling element.
 12. A method comprising: positioning a medical device assembly within a vessel at or adjacent a treatment site, the medical device assembly comprising: a tubular member having a lumen and a distal portion, an elongate shaft extending through the lumen of the tubular member, and an expandable member having a first portion coupled to the distal portion of the tubular member and a second portion releasably coupled to the elongate shaft; and releasing the second portion of the expandable member from the elongate shaft by distally advancing the elongate shaft relative to the elongate shaft, wherein when released the second portion assumes an expanded configuration in which the second portion has a greater diameter than the first portion of the expandable member.
 13. The method of claim 12, further comprising fluidly coupling the tubular member to a suction source.
 14. The method of claim 12, further comprising aspirating material into the lumen of the tubular member.
 15. The method of claim 12, wherein in the expanded configuration, the second portion of the expandable member contacts a wall of the vessel.
 16. The method of claim 12, wherein during the positioning of the medical device assembly, the first portion of the expandable member is positioned distal to the second portion of the expandable member and the second portion is at least partially disposed within the lumen of the tubular member.
 17. The method of claim 12, wherein the expandable member is self-expanding.
 18. The method of claim 12, wherein the expandable member comprises a braid.
 19. The method of claim 12, wherein the expandable member comprises an embolic filter.
 20. The method of claim 12, wherein releasing the second portion comprises breaking a coupling element connecting the second portion to the elongate shaft.
 21. The method of claim 12, wherein releasing the second portion comprises sliding the second portion out from a coupling element connecting the second portion to the elongate shaft. 